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在javascript中,将数字从10.0改为0.01

logic javascript

REDDY PRASAD Mortana · 技术社区 · 6 年前

我正在尝试实现一个函数,它在javascript中反转给定的数字(int/float)。功能实现是

function reverseNumber(n) {
    let reversed = 0;
    const sign = Math.sign(n)
    n *= sign;

    const exponent = n.toString().indexOf('.');
    if (exponent !== -1) n *= Math.pow(10, n.toString().length - 1 - exponent);
    while (n !== 0) {
        reversed *= 10;
        reversed += n % 10;
        n = Math.floor(n / 10);
    }
    if (exponent !== -1) reversed /= Math.pow(10, exponent);
    return reversed * sign;
}

此函数通过以下测试用例

  expect(reverseNumber(0)).toEqual(0);
  expect(reverseNumber(15)).toEqual(51);
  expect(reverseNumber(90)).toEqual(9);
  expect(reverseNumber(-5)).toEqual(-5);
  expect(reverseNumber(-90)).toEqual(-9);
  expect(reverseNumber(-2359)).toEqual(-9532);
  expect(reverseNumber(12.403)).toEqual(304.21);
  expect(reverseNumber(-12.4)).toEqual(-4.21);

唯一失败的情况是当输入 10.0 . 测试用例是

expect(reverseNumber(10.0)).toEqual(0.01);

我找不到任何方法来逆转 十 = & gt; 0.01 . 你们能帮忙吗? 谢谢

2 回复 | 直到 6 年前

T.J. Crowder 6 年前

function reverseNumber(num) {
    // Remember if it's negative
    var isNegative = num < 0;
    // Get the digits and decimal just for the absolute part
    var chars = (isNegative ? -num : num).toString().split("");
    // Reverse them
    chars.reverse();
    // Put it back together and convert back to a number
    var num = Number(chars.join(""));
    // Return the result, converting back to negative if appropriate
    return isNegative ? -num : num;
}

function reverseNumber(num) {
    // Remember if it's negative
    var isNegative = num < 0;
    // Get the digits and decimal just for the absolute part
    var chars = (isNegative ? -num : num).toString().split("");
    // Reverse them
    chars.reverse();
    // Put it back together and convert back to a number
    var num = Number(chars.join(""));
    // Return the result, converting back to negative if appropriate
    return isNegative ? -num : num;
}

function test(num, expect) {
    var result = reverseNumber(num);
    console.log(num, " => ", result, result == expect ? "OK" : "ERROR");
}

test(0, 0);
test(15, 51);
test(90, 9);
test(-5, -5);
test(-90, -9);
test(-2359, -9532);
test(12.403, 304.21);
test(-12.4, -4.21);

.as-console-wrapper {
  max-height: 100% !important;
}

expect(reverseNumber(10.0)).toEqual(0.01);

10 10.0 0.01 15 15.0 0.51 51

function reverseNumber(numStr) {
    // Remember if it's negative
    var isNegative = numStr[0] === "-";
    // Get the digits and decimal just for the absolute part
    var chars = (isNegative ? numStr.substring(1) : numStr).split("");
    // Reverse them
    chars.reverse();
    // Put it back together and convert back to a number
    var num = Number(chars.join(""));
    // Return the result, converting back to negative if appropriate
    return String(isNegative ? -num : num);
}

function test(num, expect) {
    var result = reverseNumber(num);
    console.log(num, " => ", result, result == expect ? "OK" : "ERROR");
}

test("0", "0");
test("15", "51");
test("90", "9");
test("-5", "-5");
test("-90", "-9");
test("-2359", "-9532");
test("12.403", "304.21");
test("-12.4", "-4.21");
test("10.0", "0.01");

Get Off My Lawn 6 年前

10.0 10 == 10.0 = true

function reverseIt(num) {
  let neg = num < 0
  let result = num.toString().replace(/^-/, '').split('').reverse().join('')
  return parseFloat(neg ? '-' + result : result)
}

console.log(reverseIt(123))
console.log(reverseIt(10))
console.log(reverseIt(1235))
console.log(reverseIt(-5310))
console.log(reverseIt(10.0.toFixed(1)))